This invention relates to apparatus for inspecting film strip material, such as, motion picture film, video and audio tape, and the like, and is more particularly concerned with improvements in the apparatus which will afford better control of the operation of the apparatus, greater efficiency, greater convenience in use, and greater safety than heretofor provided in previous designs of similar apparatus.
A number of different designs for machines, which will facilitate the inspection of motion picture film in order to locate any damage which the film may have suffered in use or any faults therein which may require repair before the film can be run through a projector with reasonable assurance that it will perform properly, are known. In the earlier designs, machines provided for this purpose included detector mechanisms of a mechanical nature. The film was guided past a spring pressed arm carrying jewel type detector elements which were arranged to contact the film surface and to react when a fault or defect appeared so as to actuate through appropriate circuitry means to quickly stop the film travel thereby enabling the operator to visually examine the fault or defect and determine the need for its elimination which required cutting the film and splicing the same minus the defective or damaged area. One such detector mechanism which has been employed successfully in machines of this type and for this purpose is disclosed in my U.S. Pat. No. 3,501,760, granted Mar. 17, 1970. Another machine employing a mechanical detector mechanism is disclosed in my U.S. Pat. No. 3,693,430, granted Sept. 26, 1972. In the machine disclosed in the latter patent the film handling mechanism is mounted on a vertical panel forming part of an upright cabinet with a work table surface below the mechanism supporting panel for accommodating auxiliary equipment such as a film splicer. The film travels in a generally horizontal path between a pair of spaced film reels, and provision is made for automatically threading the film, so that it passes through a film cleaning mechanism, a defect detector mechanism and across a work area above the work table to a driven take up reel from which it may be subsequently rewound on to the original reel at the opposite side of the support panel. Since the major operative portions of the mechanisms are mounted on the face of the support panel so as to be accessible to the operator who is positioned in front of the panel, the operator is subjected to some hazards from flying film particles in addition to the fast moving film reels which are exposed, especially when operating the machine at high speeds.
In a subsequent development the mechanical detector mechanism has been replaced by an improved defect detector mechanism which is disclosed in my U.S. Pat. No. 3,856,414, granted Dec. 24, 1974, and which employs light beams directed on the traveling film surface by means of fiber optic cables which receive light from a common light source. The light beams actuate, by direct or reflected rays, light sensors which are located in ray receiving position at the inspection station or stations. The light sensors are connected into electrical circuits controlling the film travel. The employment of light beams in the detector mechanism greatly reduces the risk of damage to the film as it passes through the detector. In this machine, as in the previous machines employing the film engaging detector mechanisms, the most convenient arrangement of the various mechanisms which operate on the film is to position the mechanisms in a generally linear path along the front face of the support panel and between the film reels where they are visible and readily accessible to the operator so that minimum time is required to monitor the operation and correct any failures in the film travel. However, as noted, the arrangement poses some operating hazards which may result in injury to the operator, particularly, when there is a failure to exercise due care on the part of the operator.
In the prior machines, control circuitry, drive mechanisms, and similar operating elements have been mounted in the area back of the vertical support panel where they are not readily accessible to the operator who is normally positioned in front of the support panel, and no means has been provided for readily adjusting some of the mechanisms so as to obtain maximum efficiency in operation.
A general object of the present invention is to provide a film inspection machine which has improved efficiency and convenience in operation and which has adequate provision for protecting the operator against injury during operation of the machine.
A more specific object of the invention is to provide, in a machine of the type described, a safety hood arrangement or visor which is retractable from a closed position covering the film reels while the machine is operating, to an out of the way open position when operation of the machine is discontinued, with control circuitry for automatic operation allowing the hood to be moved automatically to the closed position when the machine is started and to the open position upon loss of tension in the film while the machine is operating at high speed, which will occur when the film breaks or the end of the film is reached.
Another object of the invention is to provide in a film inspection machine a film cleaning arrangement which employs driven cleaning tapes arranged to present clean tape surfaces for contacting both sides of the film surface and with ready access to the tape mechanism from the operator's side of the machine.
A further object of the invention is to provide in a film inspection machine, means for operating and controlling the various work units which includes solid state circuitry with the circuits for various units on PC boards or cards which are housed in a card cage mounted on the support frame or panel which carries the work units, with the circuit boards readily accessible through a door or opening in the support frame or panel.
A still further object of the invention is to provide in a film inspecting machine circuitry for operating and controlling the work units which provides improved efficiency and control of the film handling, maximum film safety and improved operator safety so as to reduce the risk of damage to the film and minimize the risk of injury to the operator while the machine is operating.
To this end the invention as claimed herein is embodied in a machine which employs an automatically operated safety hood for covering the reel supporting portion of the face of a vertically disposed panel or frame upon which work units are mounted which comprise film cleaning, defect detecting, film viewing and film tension sensing mechanisms arranged in generally linear relation and accessible to the operator when the safety hood is in reel covering operative position, and solid state operating and control circuitry arranged for maximum convenience in the repair or replacement of the same and providing for operation of the work units so as to afford maximum convenience in handling the film and adequate safety for the operator during operation of the machine.